Growth of microorganisms outdoors is effected in a number of cases where lighting has a beneficial effect on the growth of such microorganisms. Microorganisms commonly grown outdoors are microalgae, and for the purpose of simplicity, throughout the specification reference will be made to microalgae, it being understood that this does not imply a limitation of the apparatus of the invention for growing other species, including such species which do not require light conditions for growing. Illustrative microorganisms which can be grown according to the present invention include, fungi, yeast, bacteria, macroalgae, plant cells and nematodes.